CAD Cell Planning

Portland Harbor Dredge & CAD Cell Project

Many Portland Harbor piers have not been dredged in over 70 years and are slowly filling in with sediment, decreasing water depths and causing a steady decline in available berthing for our working waterfront.

The dredge and CAD cell project goal is to provide the testing, engineering, and permitting required to determine a cost effective and environmentally responsible way to remove the contaminated dredge materials currently located in Portland Harbor.

​A CAD cell is constructed by digging a deep hole into the harbor bottom, filling it with the contaminated sediments, and capping it with a thick layer of clean sand. The EPA considers Confined Aquatic Disposal (CAD) Cells to be an environmentally safe and permanent solution for isolating contaminated sediments.

CAD cells are becoming an increasingly common solution for the clean up and isolation of contaminated dredge sediments. There are 11 CAD cells in Boston Harbor alone, and CAD cells are also found in Hyannis, Rhode Island, Connecticut, and California and as far away as Hong Kong.